Insulator with cap in socket



Aug. 2, 1960 A. WORTMANN INSULATOR WITH CAP IN SOCKET Filed Nov. 25, 1957 h WW pm m i MW K m w M1,

a G H a L id would lead to the formation of cracks.

United States Patent INSULATOR WITH CAP IN SOCKET Adolf Wortmann, 29 Rheinische Strasse, Wuppertal- Nachstebreck, Germany Filed Nov. 25, 1957, Ser. No. 698,619

Claims priority, application Germany Nov. 29, 1956- 12 Claims. (Cl. 174 200) The invention refers to a certain insulator arrangement for electrical aerial lines, embodying a metallic insulator support on to which the insulator is mounted by employing an elastic intermediate layer in form of a ca consisting of plastics. The mounting of insulators consisting of porcelain or similar insulating materials on to the supporters by means of caps of an elastic plastics material is known. These caps employed so far are provided with groined inner surfaces so as to insure an absolutely rigid mounting on the insulator support. Alternatively, they are provided with longitudinal slottings so as to warrant an easy mounting, provided that insulator supports are employed where the insulator bell is at least partly swelled opposite the shaft. However, these designs do not correspond satisfactorily with practical requirements, as they are not suited to prevent the accumulation of moisture between the end of the metallic insulator support and the bottom of the elastic cap which causes damage by corrosion at the top of the support.

The aim of the invention is to develop an insulator arrangement of the design described above, which does not only guarantee an absolutely rigid mounting of the insulator but, furthermore, protects the insulator support against damage. According to the invention this is achieved mainly by the fact that, when the support is put in place, the bottom of the elastically widening, closely tightening cap is provided for interchangeable diameters owing to its dented and arched design, and that the outer surface of the cap jacket is separated into part sections by applying springs. The application of caps which are elastically widening when the support is put in place results in the advantage that a pressure is achieved yielding a reliable tightness, so that the atmosphere cannot penetrate between the support and the inside surface of the cap. By this arrangement accumulations of moisture in the vicinity of the free end of the support are prevented and thereby damages caused by corrosion are eliminated. The application of caps with these characteristics requires great elasticity of the bottom as the necessary expansion in the bottom area is effected in various directions crossing each other, when the support is put in place, so that the plane cap bottoms which have been known so far would be exposed to an inadequate excessive strain which after a short time By means of the provision for variable diameters of the cap bottom as per this invention, the above disadvantages are eliminated as a great portion of the expansion is compensated by bendingif the surface of the bottom is uneven. Thereby, the material is only slightly stressed. A further advantage of the uneven design of the cap bottom is that eventual accumulations of moisture between the outer surface of the bottom and the ground of the hollowed insulator cannot cause damages as this space is at one side limited by the uneven bottom of the cap which forms a'flexible wall and thus achieves compensation 2,947,802 Pa tented Aug. 2, 1960 of the pressure. Therefore, no disadvantageous raises in pressure can result if the moisture freezes. The division of the outer surface of the cap jacket as per this invention results in the further advantage that the insulators can be mounted easily, firstly because the formation of air burrers is eliminated which brings about difficulties fitting the insulator, secondly because the supporting areas can be limited so that portions of the cap material can shunt even if the tolerances of the supporter diameter and the hollowed insulator are considerable. Thus the pressure will always be kept in moderate limits. In this way it is possible to give the caps suitable dimensions to insure that the cap jacket will fay the top of the supporter with considerable elastical initial tension.

The flexibility of the cap bottom can be improved by giving it a thickness smaller than the thickness of the cap jacket. In many instances it is still more advantageous to apply different grades of thickness in the various sections of the cap bottom in order to obtain equal distribution in material tension. It has been proved especially advantageous to decrease the thickness of the bottom following the line to its centre. A preferable design provides a cap bottom the surface of which is even in the outer annulus and arched in the central area, whereby the width of the annulus is limited to a space which approximately corresponds with the thickness of the cap jacket. The arching of the cap bottom is preferably arranged convex. However, it is also possible to apply an opposite arching by giving the outside surface of the bottom a concave shape.

In many instances it will be possible to manufacture the cap in one single die-pressed part. Occasionally it may be more advantageous to manufacture the bottom and the cap jacket separately and to subsequently join the parts. This construction has in some instances the advantage of better flexibility as compared to the one piece design. The joints between the separately manufactured cap bottom and the cap jacket can be carried out in various ways. It is advisable to choose for this joint a shaping connection. For the coupling areas of this kind triangular sections, for instance, may be applied. Thereby an easy mounting of the cap bottoms is warranted, and this operation may be carried out either before or after the top of the supporter has been led into the cap jacket. In cases where the coupling areas of the cap jacket and the cap bottom are desired to yield an additional flexibility, it is advisable to apply parallel side walls for the area of bearing and the locking areas, so as to warrant a uniform rigid mounting which does not depend on the respective depth of the gearing. Otherwise joints can be provided where the bottom of the cap seizes in a ring groove in the inside surface of the cap jacket. It is furthermore possible to give the cap bottom the shape of a flat cap which will seize in a ring groove fixed on the facing or on the front of the cap jacket.

It has been mentioned before that it is advisable to divide the outer jacket surface of the cap in supporting and non-supporting areas. This division is advantageously done so that theareas of the cap jacket carrying the initial tension amount to 15-80% of the total surface of the cap jacket. This provision permits to meet all requirements that ordinarily occur in practice, taking into consideration the elasticity of the material used for the manufacture of the cap-and the existing tolerances. However, in special cases deviations from the dimensions mentioned are permissible. For instance, it is occasionally sufiicient to arrange only one or a few longitudinal grooves on the surface of the cap jacket, which are chiefly air conducting channels. Owing to their smaller portion as 3 compared to the total surface of the jacket, in such cases it is only possible to compensate minor tolerances, but a largely uniform supporting of the .insulators is effected in this way. However, as in most cases considerably large tolerances of both the diameter of the supporter top and the hollowed insulator has to be taken into consideration, it will-mostly be necessary to provide a considerable portion of the surface of the cap jacket to be embodied in the areas not carrying initial tension. 7 The division may be carried out in various ways. It is possible, forinstance, to arrange longitudinal, preferably steeply spiral shaped tension areas on the outer surface of the cap jacket. These are separated by areas not carrying initial tension and situated opposite the jacket surface of the insulator hollow. In this case the tension areas may have threads adjusted to the shape of the insulator thread, this adjustment, however, may be limited to the correspondence of the lead of the threads, as in some cases deviations of the thread profiles may be advantageous to achieve a sufiiciently fixed mounting of the insulators.

For larger insulators as applied, for instance, for high tension lines, it may be sufiicient to form initial tension areas by using a comparatively small number of cams etc. only, surmounting the outer surface of the cap jacket, the diameter of the cap jacket being approximately the same as the diameter of the interior of the insulator thread. Such cams are preferably placed on one or both ends of a cap jacket only, in order to warrant an easy mounting of the insulators.

A further possibility to divide the surface of the cap jacket is to arrange a thread on the jacket surface the lead of which corresponds to that of the thread in the insulator, and the profile of which deviates from that of the insulator, so that a spiral-shaped space is left. So the surplus of the cap material is permitted to expand into this space. Furthermore, this space represents a channel for air circulation.

The drawing shows examples for the construction of the subject of the invention. These are:

Fig. 1, partly sectional side view of an insulator arrangernent,

Fig. 2, a cap, partly shown in side view, partly in longitudinal section,

Fig. 3, the unrolled jacket of the cap shown in Fig. 2,

Fig. 4, a side view of a cap of different construction,

Figs. 5 to 7, longitudinal section of various possibilities for the construction of caps, the bottom of which is manufactured separately,

Fig. 8, longitudinal section of a cap with graduated jacket surface.

The insulator arrangement shown in Fig. 1 chiefly comprises an insulator support 10, on the free end of which acap' -11 made of elastic plastics is mounted and an insulator 12 consisting of porcelain or a similar material. a jacket 13, the inside of which is smooth, and the outside is slightly swelling conically at the open end, and the jacket is closed at one end by a convex bottom 14. The convex part of the bottom 14 is surrounded by an even annulus 15. The outer surface of the cap jacket is provided with steeply spiral shaped grooves 16 which effect a division of the cap jacket into separated areas 17 carrying initial tension. The proportion of the surface of the grooves and the carrying areas is so arranged that a rigid mounting of the insulator is guaranteed, considering all possible dimensional proportions in joining of the par-ts, because the material of the cap can always expand into the spaces of the grooves. This arrangement prevents excessively high pressure in the insulator hollow and furthermore reduces the friction resistance occurring in mounting the insulator.

As shown in Fig. 3 the surface of tension carrying areas 17 as compared to the surface covered by the grooves 16 may, for instance, have the ratio that 2 bears As shown in Fig. 2 the cap 11 is provided with to 1. As marked in dot-and-dash pattern in Fig. 3 the carrying areas may be provided with jutted threads 18 in order to simplify the fitting of the insulators provided with impressed threads in the hollow.

Fig. 4 shows a modified arrangement of a cap 25 consisting of elastic plastics material which is preferably suited for larger insulators. In this instance the inside diameter of the cap jacket generally corresponds to the diameter of the insulator hollow and is bearing cams 21 only in the end area, these cams bearing on'the jacket surface of the insulator hollow with elastical in-* itial tension. If, for instance, insulators are applied where the hollows are provided with threads the cams 21 may be arranged in accordance with the lead of these threads in order to facilitate the mounting of the insulator. The elevation of the cams 21 above the outer surface of the cap jacket may be determined so that in mounting the insulator an elastical deformation of the cams is effected, so that the insulator will be sufficiently protected and be permitted to resist all influences by which it might be pulled-0E. Alternatively, the cams fitted on to the cap jacket may be replaced by separately manufactured projecting parts which are attached to the cap jacket. In this instance, the cams may be made of a material different from the material of the cap jacket, and this may be chosen either harder or softer, depending on individual requirements.

The caps shown in Figs. 5-7 represent various possibilities of construction for cap bottoms manufactured separately from the jackets, these constructions also providing for a reliable protection of the end of the insulator support against attack by penetrating moisture.

As shown in Fig. 5 a cap jacket 30 of elastic plastics and having a reinforced area 31 at one end, is provided with an annular ring groove 32 surrounding the reinforced area and faying same by a parallel surface, thereby gearing in the edge of a convex shaped bottom 33. Designs of this nature are especially suitable in cases where higher tolerances of the diameter of the supporters are to be compensated, as the gearing of parts by joining of the parallel surfaces guarantees a tight connection, irrespective of the depth of the gearing.

. A modified arrangement is shown in Fig. 6. A convex bottom 37 of a flatly swelled shape is co-ordinated to a cap jacket 35 which is hearing a ring groove 36 of an outside triangular sectioned shape, and the bottom gears in the ring groove 36 by means of its inside turned edge. The thickness of the bottom tapers in the direction to the centre. The ring groove 36 is fitted in the reinforced end area of the cap jacket 35 so that the outer dimensions of the design are reduced to permit the mounting of the insulator without difiiculties. It would, of course, also be possible to provide the arrangement shown in Fig. 6 with connection areas gearing by parallel surface connection, respectively to replace the ring groove 36 with rectangular shaped section by a 'ringgroove with parallel surface shape according to Fig. 5, although the latter is placed-in externally. Correspondingly, an arrangement as per Fig.

' 5 could also be provided with coupling areas of a triangular sectioned shape.

The arrangement shown in Fig. 7 diifers from the designs shown in Figs. 5 and 6 insofar as the connection areas are provided at the front side of an elastic cap jacket 40. For this purpose the cap jacket 40 bears on the front side a projecting swelling reinforcement 41 which is geared by a correspondingly shaped ring groove 42 of a concavely dented cap bottom 43. In certain cases designs of this nature are advantageous because of the especially simple manufacturing, as no overhanging areas are to be observed, so that the manufacture can be effected by simple pressing methods and by applying simple tools. As regards the designs shown in Figs. 5-7 it. should be mentioned that the projecting coupling area and the coupling'area taking up same are interchangeable in each case.

Fig. 8 shows the example of a design where at the end of the supporter 45 a cap is fitted,the jacket surface of which is provided with a continuous thread. The lead of this thread corresponds to the lead of a thread inside the insulator 47. The profiles of the gearing threads, however, are differing in such a way that the bottom of the thread in the cap remains unfilled, thus permitting an eventual surplus of cap material to expand into the remaining space. This space also serves the purpose of an air conducting channel.

As mentioned before, the arrangements shown are to be considered only examples for realising the invention. The invention is not restricted to these examples, but there are various other possibilities for arrangements given. The division of the outer surface of the cap jacket into tensioned and non-tensioned areas might be effected deviating from the examples shown. The variation of the diameter of the cap bottom could also be achieved by means different from the ones shown in the drawing, for instance by applying a circular ring head. The joining of separately manufactured cap jackets and bottoms could be effected by other means than shown in the drawing. The bottoms of the caps may alternatively be shaped concave or convex. The areas of the cap jacket not carrying initial tension towards the insulator hollow could be provided with shaped-in channels for the purpose of assuring air circulation. This is achieved by choosing suitable diameters, as otherwise no free air circulation on the outer surface of the cap would be warranted.

I claim:

1. An insulator arrangement for supporting electrical lines, comprising, a metallic supporting means having an outer free end portion; an inner cap of slightly elastically deformable tough non-conducting composition material comprising a substantially endless cylindrical jacket portion tightly surrounding said free end portion of said supporting means and an end portion closing one end of said jacket portion and having a curved non-planar configuration so that stresses imposed upon said end portion are absorbed therein by way of a corresponding elastic deformation of the curvature thereof; and an outer rigid insulator body surrounding said inner cap and having a closed end portion, with the outer terminal face of said free end portion of said supporting means spaced from the inner terminal face of said end portion of the insulator body so as to allow for said elastic deformation of said curvature between said terminal faces.

2. An insulator arrangement for supporting electrical lines, comprising, a metallic supporting means having an outer free end portion; an inner cap of slightly elastically deformable tough non-conducting composition material comprising a substantially cylindrical endless jacket portion tightly surrounding said free end portion of the supporting means and a thin walled end portion closing one end of said jacket portion and having a concaveconvex configuration so that stresses imposed upon said end portion are absorbed therein by way of a corresponding elastic deformation of the curvature thereof; and an outer rigid insulator body surrounding said inner cap and having a closed end portion with the outer terminal face of said free end portion of said supporting means spaced from the inner terminal face of said end portion of the insulator body so as to allow for said elastic deformation of said curvature between said terminal faces.

3. An insulator arrangement for supporting electrical lines, comprising, a metallic supporting means having an outer free end portion; an inner cap of slightly elastically deformable tough non-conducting composition material comprising a substantially cylindrical endless jacket portion tightly surrounding said free end portion of the supporting means and a thin-walled end portion closing one end of said jacket portion and having an inwardly concave and outwardly convex configuration so that stresses imposed upon said end portion are absorbed therein by way of a corresponding elastic deformation of the curvature thereof; and an outer rigid insulator body 6 surrounding said inner cap and having a closed end portion, with the outer terminal face of said free end portion of said supporting means spaced from the inner terminal face of said end portion of the insulator body so as to allow for said elastic deformation of said curvature between said terminal faces.

4. An insulator arrangement for supporting electrical lines, comprising, a metallic supporting means having an outer free end portion; an inner cap of slightly elastically deformable tough non-conducting composition material comprising a substantially cylindrical endless jacket portion tightly surrounding said free end portion of said supporting means and a thin walled end portion integral with said jacket portion closing one end of said jacket portion and having a curved non-planar configuration so that stresses imposed upon said end portion are absorbed therein by way of a corresponding elastic deformation of the curvature thereof; and an outer rigid insulator body surrounding said inner cap and having a closed end portion, with said free end portion of said supporting means spaced from the inner terminal face of said end portion of the insulator body so as to allow for said elastic deformation of said curvature between said terminal faces.

5. An insulator arrangement for supporting electrical lines, comprising a metallic supporting means having an outer free end portion; an inner cap of slightly elastically deformable tough non-conducting composition material comprising a substantially cylindrical jacket portion tightly surrounding said free end portion of the supporting means and a thin-walled separate end portion closing one end of said jacket portion and having a curved non-planar configuration so that stresses imposed upon said end portion are absorbed therein by way of a corresponding elastic deformation of the curvature thereof, said separate end portion having peripherally arranged groove and tongue connection with said jacket portion; and an outer rigid insulator body surrounding said inner cap and having a closed end portion, with the outer terminal face of said free end portion of said supporting means spaced from the inner terminal face of said end portion of the insulator body so as to allow for said elastic deformation of said curvature between said terminal faces.

6. An insulator arrangement for supporting electrical lines, comprising a metallic supporting means having an outer free end portion; an inner cap of slightly elastically deformable tough non-conducting composition material comprising a substantially cylindrical endless jacket portion tightly surrounding said free end portion of the supporting means and a thin walled separate end portion closing one end of said jacket portion and having a curved non-planar configuration so that stresses imposed upon said end portion are absorbed therein by way of a corresponding elastic deformation of the curvature thereof, said separate end portion having peripherally arranged groove and tongue snap connection with said jacket portion; and an outer rigid insulator body surrounding said inner cap and having a closed end portion, with said free end portion of said supporting means spaced from the inner terminal face of said end portion of the insulator body so as to allow for said elastic deformation of said curvature between said terminal faces.

7. An insulator arrangement for supporting electrical lines comprising a metallic supporting means having an outer free end portion; an inner cap of slightly elastically deformable tough non-conducting composition material carried by said supporting means and comprising a substantially cylindrical endless jacket portion tightly surrounding said free end portion of the supporting means, and a curved non-planar end portion closing one end of said jacket portion and providing an inner free space between said curved end portion and the free end of said supporting means; and an outer rigid insulator body surrounding said cap and having a closed end portion constituting an outer space with said end portion of the cap, so that pressure exerted in the outer space upon the cap will be compensated for by a corresponding elastic deformation of the curvature of said end portion of the cap; and means for positively securing said insulator body against axial displacement relative to said cap.

8. An insulator arrangement for supporting electrical lines comprising a metallic supporting means having an outer free end portion; an inner cap of slightly elastically deformable tough non-conducting composition material carried by said supporting means and comprising a substantially cylindrical endless jacket portion tightly surrounding said free end portion of the supporting means, and a curved non-planar end portion closing one end of said jacket portion and providing an inner free space between said curved end portion and the free end of said supporting means; and an outer rigid insulator body surrounding said cap and having a closed end portion constituting an outer space with said end portion of the cap, so that pressure exerted in the outer space upon the cap will be compensated for by a corresponding elastic deformation of the curvature of said end portion of the cap; and means for positively securing said insulator body against axial displacement relative to said cap, comprising a thread connection between said body and said cap.

9. An insulator arrangement for supporting electrical lines, comprising, a metallic supporting means having a free end portion; an inner cap of slightly elastically deformable tough non-conducting composition material carried by said supporting means and comprising a substantially cylindrical endless jacket portion tightly surrounding said free end portion of the supporting means and a curved non-planar end portion closing one end of said jacket portion and providing an inner free space between said curved end portion and the free end of the supporting means; and an outer rigid hollow insulator body surrounding said cap and having a closed end portion constituting an outer space with said outer end portion of the cap, so that pressure exerted in the outer space upon the cap will be compensated for by the corresponding elastic deformation of the curvature of the end portion of the cap; vent means formed in the outer surface of said cap for providing a vent connection be tween said outer space and the outside of said body; and means for positively securing said insulator body against axial displacement relativeto said cap.

10. An insulator arrangement for supporting electrical lines, comprising a metallic supporting means having an outer free end portion; an inner cap of slightly elastically deformable tough non-conducting composition material comprising 'a substantially cylindrical endless jacket portion tightly surrounding said free end portion of said supporting means and having outwardly directed griping portions, and an end portion closing one end of said jacket portion and having a curved non-planar configuration so that stresses imposed upon said end portion are absorbed therein by way of a corresponding elastic deformation of the curvature thereof; and an outer rigid insulator body surrounding said inner cap and having a closed end portion and being internally gripped by said outwardly directed gripping portions of the cap which provide a vent space between said cap and the surrounding body and the outer terminal face of said free end portion of said supporting means spaced from the inner terminal face of said end portion of the insulator body so as to allow for said elastic deformation of said curvature between said terminal faces.

11. An insulator arrangement for supporting electrical lines, comprising a metallic supporting means having an outer free end portion; an inner cap of slightly elastically deformable tough non-conducting composition material comprising a substantially cylindrical endless jacket portion tightly surrounding said free end portion of said supporting means, and formed with a plurality of outer open-ended grooves spaced about the periphery thereof to extend from end to end of said jacket portion so as to provide outward gripping areas between said grooves and an end portion closing one end of said jacket portion and having a curved non-planar configuration so that stresses imposed upon said end portion are absorbed therein by Way of a corresponding elastic deformation of the curvature thereof; and an outer rigid insulator body surrounding said inner cap and having a closed end portion and being internally gripped by said outwardly directed gripping areas of the cap, with said free end portion of said supporting means spaced from the inner terminal face of said end portion of the insulator body so as to allow for said elastic deformation of said curvature between said terminal faces.

12. An insulator arrangement for supporting electrical lines, comprising a metallic supporting means having an outer free end portion; an inner cap of slightly elastically deformable tough composition material comprising a substantially cylindrical endless jacket portion tightly surrounding said free end portion of said supporting means and formed with a plurality of outer open-ended grooves spaced about the periphery thereof to extend from end to end of said jacket portion spirally arranged thereon of steep pitch, and an end portion closing one end of said jacket portion and having a curved non-planar configuration so that stresses imposed upon said end portion are absorbed therein by way of a corresponding elastic deformation of the curvature thereof; and an outer rigid insulator body surrounding said inner cap and gripped by said outward gripping portion of the cap and having a closed end portion and being internally gripped by said outwardly directed gripping portion of the cap, with the outer terminal face of said free end portion of said supporting means spaced from the inner terminal face of said end portion of the insulator body so as to allow for said elastic deformation of said curvature between said terminal faces.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,885 Hubbard 06:. 5, 1954 "268,075 Brown Nov. 28, 1882 875,902 Egner Jan. 7, 1908 2,106,667 Thiry Jan. 25, 1938 2,215,152 Hosfield Sept. 17, 1940 FOREIGN PATENTS 130,231 Australia Nov. 24, 1948 

